Instrumented indentation has yielded mixed results when used to measure surface residual stresses in metal films. Relative to metals, many glasses and ceramics have a low modulus-to-yield strength (E/sy) ratio. The advantage of this characteristic for measuring residual stress using instrumented indentation is demonstrated by a series of comparative spherical and conical tip finite element simulations. Two cases are considered: (i) a material with E/s{sub y} = 24-similar to glass and (ii) a material with E/s{sub y} = 120-similar to metal films. In both cases, compressive residual stress shifts the simulated load-displacement response toward increasing hardness, irrespective of tip geometry. This shift is shown to be entirely due to pile up for the ''metal'' case, but primarily due to the direct influence of the residual stress for the ''glass'' case. Hardness changes and load-displacement curve shifts are explained by using the spherical cavity model. Supporting experimental results on stressed glasses are provided.
Non-equilibrium sorption of contaminants in ground water systems is examined from the perspective of sorption rate estimation. A previously developed Markov transition probability model for solute transport is used in conjunction with a new conditional probability-based model of the sorption and desorption rates based on breakthrough curve data. Two models for prediction of spatially varying sorption and desorption rates along a one-dimensional streamline are developed. These models are a Markov model that utilizes conditional probabilities to determine the rates and an ensemble Kalman filter (EKF) applied to the conditional probability method. Both approaches rely on a previously developed Markov-model of mass transfer, and both models assimilate the observed concentration data into the rate estimation at each observation time. Initial values of the rates are perturbed from the true values to form ensembles of rates and the ability of both estimation approaches to recover the true rates is examined over three different sets of perturbations. The models accurately estimate the rates when the mean of the perturbations are zero, the unbiased case. Finally, for the cases containing some bias, addition of the ensemble Kalman filter is shown to improve accuracy of the rate estimation by as much as an order of magnitude.
A novel hyperspectral fluorescence microscope for high-resolution 3D optical sectioning of cells and other structures has been designed, constructed, and used to investigate a number of different problems. We have significantly extended new multivariate curve resolution (MCR) data analysis methods to deconvolve the hyperspectral image data and to rapidly extract quantitative 3D concentration distribution maps of all emitting species. The imaging system has many advantages over current confocal imaging systems including simultaneous monitoring of numerous highly overlapped fluorophores, immunity to autofluorescence or impurity fluorescence, enhanced sensitivity, and dramatically improved accuracy, reliability, and dynamic range. Efficient data compression in the spectral dimension has allowed personal computers to perform quantitative analysis of hyperspectral images of large size without loss of image quality. We have also developed and tested software to perform analysis of time resolved hyperspectral images using trilinear multivariate analysis methods. The new imaging system is an enabling technology for numerous applications including (1) 3D composition mapping analysis of multicomponent processes occurring during host-pathogen interactions, (2) monitoring microfluidic processes, (3) imaging of molecular motors and (4) understanding photosynthetic processes in wild type and mutant Synechocystis cyanobacteria.
This report describes a Cooperative Research and Development Agreement (CRADA) between Salt River Project Agricultural Improvement and Power District (SRP) and Sandia National Laboratories to jointly develop advanced methods of controlling distributed energy resources (DERs) that may be located within SRP distribution systems. The controls must provide a standardized interface to allow plug-and-play capability and should allow utilities to take advantage of advanced capabilities of DERs to provide a value beyond offsetting load power. To do this, Sandia and SRP field-tested the IEC 61850-7-420 DER object model (OM) in a grid environment, with the goal of validating whether the model is robust enough to be used in common utility applications. The diesel generator OM tested was successfully used to accomplish basic genset control and monitoring. However, as presently constituted it does not enable plug-and-play functionality. Suggestions are made of aspects of the standard that need further development and testing. These problems are far from insurmountable and do not imply anything fundamentally unsound or unworkable in the standard.
This report describes efforts by the Performance Modeling and Analysis Team to investigate performance characteristics of Sandia's engineering and scientific applications on the ASC capability and advanced architecture supercomputers, and Sandia's capacity Linux clusters. Efforts to model various aspects of these computers are also discussed. The goals of these efforts are to quantify and compare Sandia's supercomputer and cluster performance characteristics; to reveal strengths and weaknesses in such systems; and to predict performance characteristics of, and provide guidelines for, future acquisitions and follow-on systems. Described herein are the results obtained from running benchmarks and applications to extract performance characteristics and comparisons, as well as modeling efforts, obtained during the time period 2004-2006. The format of the report, with hypertext links to numerous additional documents, purposefully minimizes the document size needed to disseminate the extensive results from our research.
This study characterizes theoretical and industry approaches to organizational capabilities management and ascertains whether there is a distinct ''best practice'' in this regard. We consider both physical capabilities, such as technical disciplines and infrastructure, and non-physical capabilities such as corporate culture and organizational procedures. We examine Resource-Based Theory (RBT), which is the predominant organizational management theory focused on capabilities. RBT seeks to explain the effect of capabilities on competitiveness, and thus provide a basis for investment/divestment decisions. We then analyze industry approaches described to us in interviews with representatives from Goodyear, 3M, Intel, Ford, NASA, Lockheed Martin, and Boeing. We found diversity amongst the industry capability management approaches. Although all organizations manage capabilities and consider them to some degree in their strategies, no two approaches that we observed were identical. Furthermore, we observed that theory is not a strong driver in this regard. No organization used the term ''Resource-Based Theory'', nor did any organization mention any other guiding theory or practice from the organizational management literature when explaining their capabilities management approaches. As such, we concluded that there is no single best practice for capabilities management. Nevertheless, we believe that RBT and the diverse industry experiences described herein can provide useful insights to support development of capabilities management approaches.
A relatively new concept in the field of mechanical shock analysis has been introduced whereby an analysis is made on the work done on structures by the excitation force. The energy imparted to a structure by the excitation can then be divided into various storage and loss mechanisms within the structure. These energies can be used to both evaluate shock response severity and characterize the underlying excitation. Previous work has illustrated the many advantages of the energy methods over traditional shock response spectrum techniques. This work will show that the energy delivered to a MDOF system is uncoupled between modes. Therefore, the total deformational energy delivered to a MDOF system is a weighted sum of the uncoupled modal contributions. This leads to the ability to compute input energy on a modal basis using uncoupled, SDOF calculations. Further, the internal storage and loss energies are also uncoupled. When the input excitation is broadband, the energy input into a MDOF structure by ground motion is dominated by that mode with the largest fraction of participating mass, often the fundamental mode of the system. This leads to the justification for treating complex structures as SDOF oscillators when using energy methods to evaluate both the underlying excitation and the structural response.
This paper highlights key topic areas to be discussed the authors in a panel format during the Augmented Cognition thematic area paper session: 'Augmented Cognition Lessons Learned and Future Directions for Enabling 'Anyone, Anytime, Anywhere' Applications'. The term 'killer app' has been part of the vernacular in the commercial computer software and electronic devices industry to refer to breakthrough technologies [2]. A 'killer app' generally emerges with the development of related technologies that extends over some time and involves numerous variations on a basic concept. Hypotheses may be offered with respect to the conditions that will be needed to enable a similar situation with augmented cognition technologies. This paper and resulting panel session will address the numerous concepts that have emerged from the augmented cognition field to date and postulate how and when this field's first 'killer app' may emerge (e.g., 5, 10, 15, or more years from now).
A velocity interferometer system for any reflector (VISAR) was recently deployed at the light initiated high explosive facility (LIHE) to measure the velocity of an explosively accelerated flyer plate. The velocity data from the flyer plate experiments, using the vendor's fringe constant of 100m/s/fringe, were consistently lower than model predictions. The goal of the VISAR validation test series was to confirm the VISAR system fringe constant. A low velocity gas gun was utilized to impact and accelerate a target at the LIHE facility. VISAR velocity data from the accelerated target was compared against an independent velocity measurement. The data from this test series did in fact reveal the fringe constant was significantly higher than the vendor's specification. The correct fringe constant for the LIHE VISAR system has been determined to be 123 m/s/fringe. The Light Initiated High Explosive (LIHE) facility recently completed a Phase I test series to develop an explosively accelerated flyer plate (X-Flyer). The X-Flyer impulse technique consists of first spraying a thin layer of silver acetylide silver nitrate explosive onto a thin flyer plate. The explosive is then initiated using an intense flash of light. The explosive detonation accelerates the flyer across a small air gap towards the test item. The impact of the flyer with the test item creates a shock pulse and an impulsive load in the test unit. The goal of Phase I of the X-Flyer development series was to validate the technique theory and design process. One of the key parameters that control the shock pulse and impulsive load is the velocity of the flyer at impact. To measure this key parameter, a velocity interferometer system for any reflector (VISAR) was deployed at the LIHE facility. The VISAR system was assembled by Sandia personnel from the Explosive Projects and Diagnostics department. The VISAR was a three leg, push-pull system using a fixed delay cavity. The primary optical components consisted of a delay bar and stand off that holds the air-reference mirror. When this component was ordered 2 years ago, a fringe constant of 100 m/s/fringe for a 532nm laser was specified. The fabrication/assembly vendor went out of business shortly after delivering the component and did not deliver the certification papers with the component. The vendor documentation to verify the fringe constant was not made available to Sandia. VISAR systems were generally not calibrated because the fringe constant could be determined from a known glass index of refraction and length. The VISAR system was deployed at the LIHE facility using the specified 100m/s/fringe. The Phase I X-Flyer development series was completed successfully measuring flyer velocities using the VISAR system. However flyer velocity measurements were on average 18% lower than analytical model predictions. In an effort to resolve the consistently slow velocity data, the VISAR data was under scrutiny. The purpose of the LIHE VISAR validation test series is to verify the velocity data taken with the VISAR system.
Verification and validation (V&V) are the primary means to assess the accuracy and reliability of computational simulations. V&V methods and procedures have fundamentally improved the credibility of simulations in several high-consequence fields, such as nuclear reactor safety, underground nuclear waste storage, and nuclear weapon safety. Although the terminology is not uniform across engineering disciplines, code verification deals with assessing the reliability of the software coding, and solution verification deals with assessing the numerical accuracy of the solution to a computational model. Validation addresses the physics modeling accuracy of a computational simulation by comparing the computational results with experimental data. Code verification benchmarks and validation benchmarks have been constructed for a number of years in every field of computational simulation. However, no comprehensive guidelines have been proposed for the construction and use of V&V benchmarks. For example, the field of nuclear reactor safety has not focused on code verification benchmarks, but it has placed great emphasis on developing validation benchmarks. Many of these validation benchmarks are closely related to the operations of actual reactors at near-safety-critical conditions, as opposed to being more fundamental-physics benchmarks. This paper presents recommendations for the effective design and use of code verification benchmarks based on manufactured solutions, classical analytical solutions, and highly accurate numerical solutions. In addition, this paper presents recommendations for the design and use of validation benchmarks, highlighting the careful design of building-block experiments, the estimation of experimental measurement uncertainty for both inputs and outputs to the code, validation metrics, and the role of model calibration in validation. It is argued that the understanding of predictive capability of a computational model is built on the level of achievement in V&V activities, how closely related the V&V benchmarks are to the actual application of interest, and the quantification of uncertainties related to the application of interest.
Nd:YAG laser joining is a high energy density (HED) process that can produce high-speed, low-heat input welds with a high depth-to-width aspect ratio. This is optimized by formation of a ''keyhole'' in the weld pool resulting from high vapor pressures associated with laser interaction with the metallic substrate. It is generally accepted that pores form in HED welds due to the instability and frequent collapse of the keyhole. In order to maintain an open keyhole, weld pool forces must be balanced such that vapor pressure and weld pool inertia forces are in equilibrium. Travel speed and laser beam power largely control the way these forces are balanced, as well as welding mode (Continuous Wave or Square Wave) and shielding gas type. A study into the phenomenon of weld pool porosity in 304L stainless steel was conducted to better understand and predict how welding parameters impact the weld pool dynamics that lead to pore formation. This work is intended to aid in development and verification of a finite element computer model of weld pool fluid flow dynamics being developed in parallel efforts and assist in weld development activities for the W76 and future RRW programs.
This report is a review of progress made by the Center for the Simulation of Accidental Fires and Explosions (C-SAFE) at the University of Utah, during the ninth year (Fiscal 2006) of its existence as an activity funded by the Department of Energy's Advanced Simulation and Computing Program (ASC). The ten-member Review Team composed of the TST and AST spent two days (August 24-25, 2006) at the University, reviewing formal presentations and demonstrations by the C-SAFE researchers and conferring privately. The Review Team found that the C-SAFE project administrators and staff had prepared well for the review. C-SAFE management and staff openly shared extensive answers to unexpected questions and the advance materials were well prepared and very informative. We believe that the time devoted to the review was used effectively and hope that the recommendations included in this 2006 report will provide helpful guidance to C-SAFE personnel and ASC managers.
This paper presents constitutive models for the anisotropic, finite-deformation viscoelastic behavior of soft fiber-reinforced composites. An essential assumption of the models is that both the fiber reinforcements and matrix can exhibit distinct time-dependent behavior. As such, the constitutive formulation attributes a different viscous stretch measure and free energy density to the matrix and fiber phases. Separate flow rules are specified for the matrix and the individual fiber families. The flow rules for the fiber families then are combined to give an anisotropic flow rule for the fiber phase. This is in contrast to many current inelastic models for soft fiber-reinforced composites which specify evolution equations directly at the composite level. The approach presented here allows key model parameters of the composite to be related to the properties of the matrix and fiber constituents and to the fiber arrangement. An efficient algorithm is developed for the implementation of the constitutive models in a finite-element framework, and examples are presented examining the effects of the viscoelastic behavior of the matrix and fiber phases on the time-dependent response of the composite.
I am pleased to present the CFO's FY06 Financial Report for Sandia National Laboratories (SNL). As a contractor to DOE and other government agencies, the bulk of SNL's revenue is from tax dollars. SNL's FY06 total revenue, total expenditures, and total employment levels were slightly below the FY05 record high levels. Throughout FY06, SNL business staff continued to improve SNL's financial stewardship of entrusted taxpayer funds through implementation of best-in-class practices in financial business operations and internal control policies and procedures to ensure compliance with all accounting standards and provide accountability to our customers. Our FY06 efforts focused on process certification and improvement, implementing OMB Circular A-123, achieving assurance activities, implementation of a Financial Management Competency Program throughout SNL, and continuous assessment of trends and emerging issues.